Vadose-zone characteristic pollutants distribution, microbial community structure and functionality changes in response to long-term leachate pollution of an informal landfill site.

The study embarked on a comprehensive examination of the evolution and diversity of microorganisms within long-term leachate pollution environments, with a focus on varying depths and levels of contamination, and its linkage to soil characteristics and the presence of heavy metals. It was observed that microbial diversity presented distinct cross-depth trend, where archaeal communities were found to be particularly sensitive to alterations in soil depth. Noteworthily, Euryarchaeota increased by 4.82 %, 7.64 % and 9.87 % compared with topsoil. The abundance of Tahumarchaeota was successively reduced by 5.79 %, 9.58 %, and 12.66 %. The bacterial community became more sensitive to leachate pollution, and the abundance of Protebacteria in contaminated soil decreased by 10.27 %, while the abundance of Firmicutes increased by 7.46 %. The bacterial genus Gemmobacter, Chitinophaga and Rheinheimera; the archaeal genus Methanomassiliicoccus and Nitrosopumilus; along with the fungal genus Goffeauzyma, Gibberella, and Setophaeosphaeria emerged as pivotal biological markers for their respective domains, underpinning the biogeochemical dynamics of these environments. Furthermore, the study highlighted that geochemical factors, specifically nitrate (NO3--N) levels and humic acid (HA) fractions, played crucial roles in modulating the composition and metabolic potential of these communities. Predictive analyses of functional potentials suggested that the N functional change of archaea was more pronounced, with anaerobic ammonia oxidation and nitrification decreased by 15.78 % and 14.62 %, respectively. Overall, soil characteristics alone explained 57.9 % of the total variation in the bacterial community structure. For fungal communities within contaminated soil, HMs were the primary contributors, explaining 46.9 % of the variability, while soil depth accounting for 6.4 % of the archaeal variation. This research enriches the understanding of the complex interrelations between heavy metal pollution, soil attributes, and microbial communities, paving the way for informed strategies in managing informal landfill sites effectively.

Antioxidant Enzyme Activities and Lipid Oxidation in Rape (Brassica campestris L.) Bee Pollen Added to Salami during Processing.

The present research investigated the antioxidant effect of rape (Brassica campestris L.) bee pollen (RBP) on salami during processing. Eight flavonoids in RBP ethanol extract were quantified by high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis, and quercetin, rutin, and kaempferol were the major bioactive compounds. The RBP ethanol extract exhibited higher total antioxidant capacity than 6-hydroxy-2,5,7,8-tertramethylchromancarboxylic acid (trolox) at the same concentration. The salami with 0.05% RBP extract had higher catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activities than that of the control throughout the processing time (p < 0.05). Significant decreases in peroxide value (POV) and thiobarbituric acid-reactive substances (TBARS) were obtained in the final salami product with 0.05% RBP ethanol extract or 1% RBP (p < 0.05). These results suggested that RBP could improve oxidative stability and had a good potential as a natural antioxidant for retarding lipid oxidation.